Preheat the oven to 350F and line a baking sheet with parchment paper.
In a large bowl, stir together the almond flour, maple syrup, oil, salt, matcha, peppermint, baking soda, and vinegar. The batter should be smooth and slightly sticky.
Use a tablespoon to scoop the dough onto a lined baking sheet, making roughly 16 cookies. Press the mounds with your finger tips to flatten and shape them into circle cookie shapes. (Get your fingertips wet to help prevent the dough from sticking to your hands as you flatten them.)
Bake the cookies until dry around the edges, about 12 minutes. (They won't be golden or brown in color.) Cool completely before decorating with the melted chocolate. (I sometimes place the cookies in the freezer for 20 minutes or so to speed the process.)
To melt the chocolate, place the chocolate chips in a double boiler and heat until melted, stirring occasionally. Remove the chocolate from the heat once it’s smooth.
Dip each cooled cookie halfway into the melted chocolate. I tip the cookie forward, so that mostly the front half of the cookie gets dipped. (I don’t care about the back of the cookies as much.) Place the cookies in the freezer for about 5 minutes to set the chocolate, then remove them again and use the tines of a fork to drizzle the remaining melted chocolate over them, for a decorative look.
Let the chocolate harden at room temperature, then serve. Leftover cookies can be stored at room temperature for up to 3 days, but they will get softer if you keep them in an airtight container. For a firmer cookie that lasts longer, store these in an airtight container in the fridge for up to 2 weeks, or in the freezer for up to 3 months.
*Normally, I use almond meal and almond flour interchangeably, but I suggest using blanched almond flour in this recipe to get the prettiest green color. Blanched almond flour produces more of a shortbread-like chocolate chip cookie with slightly crisp edges and a soft center, while almond meal (with the skins) will produce a softer, more cake-like cookie.